Traumatic brain injuries:

Special operators (SO) and specific attached personnel are repeatedly experiencing mild traumatic brain injuries (TBI) during normal training cycles. The Centers for Disease Control and Prevention defines a TBI as “a disruption in the normal function of the brain that can be caused by a bump, blow, or jolt to the head, or penetrating head injury.”

Conditions and symptoms linked to TBIs include headaches, irritability, sleep disorders, depression, slower thinking and memory problems. As these conditions can affect life in and out of the military, it is important to study their effects and determine potential causal factors.

The Investigating Training Associated Blast Pathology (INVICTA) study, conducted by Dr. Michael J. Roy, professor of medicine at the Uniformed Services University (USU) and director of operational research for USU’s Center for Neuroscience and Regenerative Medicine, is looking into the short- and long-term effects of repeated subconcussive blast exposures on special operators and related personnel.

The INVICTA study includes wearing three sensors spaced on the operator’s body to determine the amount of pressure they are exposed to throughout a work-up cycle. The effects of these exposures are still being studied to determine potential longterm effects. There is growing concern that the result of multiple concussive events over a lifetime is cumulative.

INVICTA is looking at SEALs during the heavy weapons phase of training and studying instructors who conduct the training six times per year. They are evaluating the cumulative effect of smaller subconcussive events over the course of three to 18 months to see the immediate aftermath and long-term effects of repeated exposure on the brain. To do this, the researchers will use the sensors and how this training affects memory, attention span, reaction time, and neuroimaging.

While firing standoff weapons like rocket launchers and the Carl-Gustaf recoilless rifle, operators are repeatedly exposed to relatively large amounts of force. Early in my career, we were told we could only fire or serve as the loader for five rounds per day because any more exposure would begin to tear the aorta off your heart. Now our limit is three per day because that overpressure is enough to give you a mild TBI.

Several other weapon systems also have a potential impact. For example, the 50-caliber sniper platform with a muzzle brake can create a large amount of overpressure felt by the operator and spotter. Anything above 4 pounds per square inch (psi) is considered unsafe and can contribute to TBI.

While training with 50-caliber sniper rifles shooters and spotters are routinely exposed to 3.8–4.5 psi. As the shooter is directly behind the gun they do not receive the same exposure. When we take turns as the spotter, it always felt like a mild slap in the face